Reinstall previous behavior for Set and Queue toString.

sdk/lib/collection/list.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.collection;
 
-/** A reusable set used to identify cyclic lists during toString() calls. */
-Set _toStringVisiting = new HashSet.identity();
-
 /**
  * Abstract implementation of a list.
  *
  * All operations are defined in terms of `length`, `operator[]`,
  * `operator[]=` and `length=`, which need to be implemented.
  *
  * *NOTICE*: Forwarding just these four operations to a normal growable [List]
  * (as created by `new List()`) will give very bad performance for `add` and
  * `addAll` operations of `ListBase`. These operations are implemented by
  * increasing the length of the list by one for each `add` operation, and
  * repeatedly increasing the length of a growable list is not efficient.
  * To avoid this, either override 'add' and 'addAll' to also forward directly
  * to the growable list, or, preferably, use `DelegatingList` from
  * "package:collection/wrappers.dart" instead.
  */
-abstract class ListBase<E> = Object with ListMixin<E>;
+abstract class ListBase<E> extends Object with ListMixin<E> {
+  /**
+   * Convert a `List` to a string as `[each, element, as, string]`.
+   *
+   * Handles circular references where converting one of the elements
+   * to a string ends up converting [list] to a string again.
+   */
+  static String listToString(List list) =>
+      IterableBase.iterableToFullString(list, '[', ']');
+}
 
 /**
  * Base implementation of a [List] class.
  *
  * This class can be used as a mixin.
  *
  * This implements all read operations using only the `length` and
  * `operator[]` members. It implements write operations using those and
  * `length=` and `operator[]=`
  *
@@ skipping 458 matching lines @@
       setRange(index, index + iterable.length, iterable);
     } else {
       for (E element in iterable) {
         this[index++] = element;
       }
     }
   }
 
   Iterable<E> get reversed => new ReversedListIterable(this);
 
-  String toString() {
-    if (_toStringVisiting.contains(this)) {
-      return '[...]';
-    }
-
-    var result = new StringBuffer();
-    try {
-      _toStringVisiting.add(this);
-      result.write('[');
-      result.writeAll(this, ', ');
-      result.write(']');
-     } finally {
-       _toStringVisiting.remove(this);
-     }
-
-    return result.toString();
-  }
+  String toString() => IterableBase.iterableToFullString(this, '[', ']');
 }